The present invention relates to chair controls. Chair controls are devices mounted underneath the seat of the chair typically to control the tilting of the chair when a person leans back in it. They usually comprise a stationary member adapted to be mounted on a pedestal base and a tiltable member or members pivotally mounted to the stationary member. The tiltable member is then secured to the chair seat or back. There is a bias member or energy storing device which controls the rate at which one can tilt rearwardly in the chair with the application of a given force and which returns the chair to its normal position when the user stops leaning back. Many users of tilter chairs consider it desirable to be able to lock the chair against tilting. While it is nice to be able to lean back in a chair and think or reflect about a particular project, there are also "doing" tasks where it is nice to sit up to your desk and still receive some support from your chair when you lean back in it. To perform such "doing" tasks, some users like to be able to lock their chair control against tilting motion.
Such locking devices have been proposed in prior art chair controls. U.S. Pat. No. 2,991,125 discloses some type of chair control in which a small cylinder is mounted between the base and back of the chair, which cylinder can be locked against movement to thereby lock the chair against tilting action. U.S. Pat. No. 3,602,537 to Kerstholt and U.S. Pat. No. 4,062,587 to Wolters disclose another type of locking mechanism wherein members which are normally movable with respect to one another can be clamped tightly against one another to prevent movement.
These mechanisms are complex in construction. Further, parts which are normally movable with respect to each other are placed under a good deal of stress by being clamped against one another. The mechanisms doing the clamping and locking action are accordingly subject to wear and tear.